x11proto-dev 2018.4-4 (armhf binary) in ubuntu bionic

 This package provides development headers describing the wire protocol
 for the X11 core and extension protocols, and also provides a number of
 utility headers, used to abstract OS-specific functions.
 .
 More information about X.Org can be found at:
 <URL:https://www.X.org>
 .
 This package is built from the X.org xorgproto module.